FreeBSD HA file cluster possibilities

[RIck van der Zwet]

I been (re)searching and reading what the options are with regards to 
H(igh) A(vailablility) file storage using FreeBSD, but cannot yet find a 
proper working solution. Any advice welcome!

I like to be able to mirror a full identical disk between two server. So 
in case of hardware failure of server A (Master). Server B (Slave) 
immediately takes over, without any loss of data. The Network 
configuration is easy using ucarp/vppr. But the file system is the hard 
part. Paths I have investigated:

a) ggate & gmirror: Export system on Server B to Server A. Use gmirror 
on Server A to keep identical disks. When the ggated on Server B 
actually goes down, the whole setup freezes, until the ggated is back up 
again. Second on network delays gmirror looses, having to sync all over 
again. Leaving the machine at risk.

b) SAN/iSCSI targets/gmirror: [Brainstorm] Have 2 iSCSI storage boxes 
namely C and D. Have Server A run gmirror on the C and D. And let B 
pickup on failure? Does this work?

c) ssync/rsync: This does not suit the needs as it does not provide 
realtime mirroring. Causing data-loss on failure. As rsync/ssync does 
not run in realtime.

d) drbd: http://www.drbd.org/ - Does anyone has a working (alternative) 
setup on FreeBSD?


Any other solution/setup I am missing? Using external hardware/software 
is all-right as long I am able to connect to FreeBSD with it and it 
leaves no single point of failure.

Thanks in advance!
/Rick